A great many different types of machines are powered primarily or in part with electric drive systems. Examples include electrically propelled land and water vehicles, industrial equipment, elevators, and many others. Like all mechanical and electromechanical systems fatigue can occur over time, leading to performance degradation or failure. Manufacturing tolerances and other factors such as duty cycle and environmental conditions can affect the likelihood of failure at any given time, and thus great variation in the field service life of electric drives is observed. The industry is therefore welcoming of advances in relation to detecting and predicting failure.